This invention relates to a pad type journal bearing device used for a main guide bearing of high precision in a high speed rotary machinery such as turbines and compressors or machine tools, and more particularly, to a pad type journal bearing device with a constant bearing clearance.
In prior pad type journal bearing devices, bearing pads are constructed so as to be capable of slightly tilting in a circumferential direction with the aid of positioning pins disposed between adjacent bearing pads, or constructed such that when the device is not mounted on a rotating shaft to be loose, they can shift radially inwardly away from a casing to the extent the device does not become completely disassembled. When a rotating shaft is inserted into a bearing device of such a structure in order that the bearing device may be used as a tilting pad type journal bearing, a bearing clearance between the rotating shaft and the bearing pads is apt to be inconstant and nonuniform. Consequently, breakage of a lubricating oil film produced due to poor lubricating action degrades the follow-up capability at the time of start-up and suspension, and, in particular, causes vibrations and noises at the time of start-up.